If you’re planning to trade in your old phone, it’s worth considering an underutilized way to buy your next one: Apple’s iPhone Upgrade Program.

For the uninitiated, the program is essentially an interest-free loan: The full cost of your iPhone and AppleCare Plus is spread out over two years with 24 installments. Once you’ve paid the full amount, the phone is yours. Or you have the option to upgrade after making at least 12 payments. When you go to the Apple Store, you have to ask for the upgrade program specifically, since you can also pay up front for the iPhone.

In 2015, I bought the iPhone 6S Plus this way after trading in an iPhone 5 I had held onto — or, more accurately, dropped a bunch of times — for over two years. In 2016, I upgraded to the iPhone 7 Plus through the program, and this September I plan to get whatever Apple unveils next.

It’s not because I’m a tech enthusiast who has to have the latest and greatest gadget — although I admit it’s nice to get a new iPhone every year, and switching is seamless thanks to Google Photos and contact syncing. My reasons for converting to Apple’s upgrade program are primarily financial.

1. Unless your carrier offers a rebate or discount, you’re not paying less to buy your iPhone through it.

Most iPhone users — 92% — have no plans to ditch Apple’s decade-old device for a different brand. But only 12% buy their iPhone directly from Apple, according to data from Consumer Intelligence Research Partners. Three out of four people still head to their wireless carrier to buy a new iPhone, even though the days of subsidies and incentives in exchange for wireless contracts are behind us.

“With all the publicity that Apple garners for its own stores, it’s kind of an overlooked fact that the carriers by far sell the most phones in the US, ” said Michael Levin, a partner and cofounder of CIRP.

Many wireless carriers offer similar instalment programs, and some even appear to be less expensive. But it’s important to understand that the price you pay for the phone — retail price — is the same. If the monthly amount is less, it’s probably because you will make payments over a longer period or because it doesn’t include AppleCare Plus.

2. Waiting to upgrade doesn’t save that much, and it puts you at risk of damaging or losing your phone.

Many people hold onto their iPhones for 30 months before upgrading, according to Jim Suva, a senior analyst at Citigroup. While that may seem financially wise, it’s not exactly something to be smug about, if you do the maths.

Let’s say you buy a new iPhone 7 Plus for $US769 and add AppleCare Plus for $US129, for a total of $US898, not including tax. If you keep it for 22 months before upgrading — the current average — your monthly cost breaks down to about $US41. You pay $US5 less per month if you purchase it through the upgrade program instead.

Not only would you pay less per month, but you’d have to hold the phone for only one year before getting a new one.

Even if you decide to buy a new iPhone without AppleCare Plus, use it for 30 months, and then resell it, the amount you save isn’t astronomical. Let’s say you buy it for $US769 and sell it back to Apple after 30 months for $US135. In that scenario, your all-in cost is $US21 a month.

While that may be less expensive, saving $US16 a month for an item you touch 2,617 times a day may not be worth it. You’d save more by reducing your rent or negotiating your cable bill. Plus, by planning to keep the phone for so long, you take on the risk that your screen cracks or you drop it in a pool before you’re ready to resell it.

I’ve bought an iPhone using both approaches, and for me the decision is clear. I would prefer to pay $US37 a month to know my phone is covered and that I can get a new one every September than to pay $US21 a month and have to worry about keeping it in good shape for years.

3. AppleCare Plus is the best tech support for your iPhone, hands down.

Last year, I made the mistake of typing an email on my iPhone while walking on an elevated subway platform after a rainstorm (a terrible idea no matter the weather, I know). I didn’t get very far before I tripped, sending my iPhone flying. There was a collective gasp as it slid along the platform and tipped over the edge, dropping to its death 30 feet below.

Once I picked up the busted phone from the street, I got back on the subway and headed directly to an Apple Store. Even without an appointment, it took less than an hour to walk away with a shiny, new replacement iPhone.

My out-of-pocket cost was $US99 instead of the $US869 it would have cost to purchase a new phone. Considering the original was only a few weeks old, I was elated to have AppleCare Plus.

If I had mobile phone insurance through my carrier instead, getting it fixed would have required more time and effort on my part. Plus, at about $US5 a month through the upgrade program, AppleCare Plus is cheaper than most mobile phone insurance plans.

4. Having an unlocked phone gives you options if you want to resell it or switch carriers.

Your monthly mobile phone plan probably costs more than your monthly iPhone payment, so having the ability to switch providers if you find a better deal is important.

If you buy your phone directly from a wireless provider, you may not be signing up for a contract, but that doesn’t mean you aren’t locked into that carrier. To switch carriers, you’d have to pay your remaining balance in full, immediately. And your iPhone may not work as well — or at all — on a different network.

When you buy your iPhone at the Apple Store, you have the option of getting an unlocked version. That means it will work with any wireless carrier, and you can switch providers at will.

Apple’s iPhone Upgrade Program won’t work for everyone. There are a few downsides to consider:

AppleCare Plus doesn’t cover you for a lost or stolen phone (though your home or renters insurance might).

To qualify, you’ll have to have good credit, because you’re essentially taking out a loan.

You’ll also have to fork over the full sales-tax amount up front, which means your first payment is likely to be over $US100.